Thanks, Bill D, that was thoughtful. It does look like there's something there, but I'm not knowledgeable enough to recognize it. I'm thinking it might be something as simple as a piezo-electric quartz wafer. A transducer, in the general sense, is anything that converts one form of energy into another. A microphone is a transducer that converts mechanical energy (diaphragm motion caused by air wave pulsations) into electrical energy (a weak audio signal). Piezo-electric quartz converts electrical energy into mechanical energy (in an electronic clock , for example) and vice-versa (I believe it's what Ovation uses for their factory bridge pick-ups).